From: Mindblindness: ern essay on
autism end theor-y of mind.
Simon Baron-Cohen. lgg5.
Cambridge, MH: MIT Press.
Mindblindness
An Essay on Autism and Theory of Mind
kcLearning, Development, and Conceptual Change
Simon Baron-Cohen
Lila Gleitman, Susan Carey, Elissa Newport, and Elizabeth
Spelke, editors
JohnMacnamara, Namesfir Things: A Study in Human Learning (1982)
Susan Carey, Conceptual Change in Childhood (1985)
David Premack, "Gavagai!" or the Future Histoy of the Animal Language
Controversy (1986)
Daniel N. Osherson, Systems That LPnrn: A n Introduction to Learning Theoyfor
Cognitive and Computer Scientists (1986)
JamesL. Morgan, From Simple Input to Complex Grammar (1986)
Frank C. Keil, Concepts, Kinds, and Cognitive Dmlopment (1989)
Steven Pinker, Learnability and Cognitia: The Acquisition of Argument Structure
(1989)
Kurt VanLehn, Mind Bugs: The Origins of Procedural Misconception (1990)
Ellen M. Markman, categorization and Naming in Children: Problems oflnduction
(1990)
Henry M. Wehan, The Child's T h w y ofMind (1990)
Charles R Gallistel, The Organization of Learning (1990)
Josef Pemer, Understanding the Representational Mind (1991)
Eleanor J. Gibson, An Odyssey in Learning and Perception (1991)
Annette Karmiloff-Smith, Beyond Modularity: A Dewlopmental Perspective on
Cognitive Science (1992)
Simon Baron-Cohen, Mindblindness: An Essay on Autism and Theoy #Mind
(1995)
A Bradford Book
The MIT Press
Cambridge, Massachusetts
London, England
Tooby, J, & Cosmides, L. (1995). The language of the eyes as an
evolved language of mind. Forward to: Mindblindness: An essay
on autism and theory of mind. By Simon Baron-Cohen.
Cambridge, MA: MIT Press.
Foreword
Just as common sense is the faculty that tells us that the world is
flat, so too it tells us many other things that are equally unreliable. It tells us, for example, that color is out there in the world,
an independent property of the objects we live among. But scientific investigations have led us, logical step by logical step, to
escape our fanatically insistent, inelastic intuitions. As a result,
we know now that color is not already out there, an inherent
attribute of objects. We know this because we sometimes see
physically identical objects or spectral arrays as having different
colors-depending on background, circumstance, and contextand we routinely see physically different spectral arrays as having the same color. The machinery that causes these experiences
allows us to identify something as the same object across situations despite the different wavelength composites that it reflects
from circumstance to circumstance. Far from being a physical
property of objects, color is a mental property-a useful invention that specialized circuitry computes in our minds and then
"projects onto" our percepts of physically colorless objects. This
invention allows us to identify and interact with objects and the
world far more richly that we otherwise could. That objects
seem to be colored is an invention of natural selection, which
built into some species, including our own, the specialized neural circuitry responsible.
What is true for color is true for everything in our experienced
worlds: the warmth of a smile, the meaning of a glance, the heft
of a book, the force of a glare. Although it is a modern truism to
say that we live in culturally constructed worlds, the thin surface
of cultural construction is dwarfed by (and made possible by)
the deep underlying strata of evolved species-typical cognitive
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Foreword
construction. We inhabit mental worlds populated by the computational outputs of battalions of evolved, specialized neural
automata. They segment words out of a continual auditory flow,
they construct a world of local objects from edges and gradients
in our two-dimensional retinal arrays, they infer the purpose of
a hook from its shape, they recognize and make us feel the negative response of a conversational partner from the roll of her
eyes, they identify cooperative intentions among individuals
from their joint attention and common emotional responses, and
so on.
Each of the neural automata responsible for these constructions is the carefully crafted product of thousands or millions of
generations of natural selection, and each makes its own distinctive contribution to the cognitive model of the world that
we individually experience as reality. Because these devices are
present in all human minds, much of what they construct is the
same for all people, from whatever culture; the representations
produced by these universal mechanisms thereby constitute the
foundation of our shared reality and our ability to communicate.
Yet, because these evolved inference engines operate so automatically, we remain unaware of them and their ceaseless,
silent, invisible operations. Oblivious to their existence, we mistake the representations they construct (the color of a leaf, the
irony in a tone of voice, the approval of our friends, and so on)
for the world itself-a world that reveals itself, unproblematically, through our senses.
Indeed, it is exactly because of their universal and automatic
character that we have been blind to the existence of the machinery that constitutes most of the evolved architecture of the
human mind-what might reasonably be called our cognitive
instincts. Instinct blindness is sanity for the individual, but it has
been crippling for scientific psychology. Scientists do not conduct research to find things whose existence they don't suspect.
These mechanisms solve the many computational problems
involved in constructing the world we deal with so automatically that the scientific community remained unaware for decades
that these computational problems existed and were being
Foreword
xiii
solved as part of the ordinary functioning of the mind of every
normal human being. As a consequence, most of psychology
retained its empiricist orientation throughout the 20th century,
resting on the assumption that a pre-packaged "world" acted
though the senses and through general-purpose learning mechanisms to build our concepts, interpretative frameworks, and
mental organization.
In the last two decades, though, scientific psychology has
finally begun to slip the bonds imposed by this seductive but
misdirecting folk psychology. Cognitive scientists were awakened by a series of encounters with alien minds, whose starkly
contrasting designs and surprising incapacities drew attention
to previously overlooked natural human competences and to
the computational problems they rou tinef y solve. They encountered artificial mentalities in the computer lab that had obstinate
difficulties in seeing, speaking, handling objects, understanding,
or doing almost anything that humans do effortlessly. They
encountered thousands of animal species each of which could
solve a striking diversity of natural information-processing
problems that other species could not. They encountered the
developing minds of infants and children, which forced them to
confront the intractable computational and philosophical problems that plague empiricist models of how children acquire
knowledge. And they encountered neurologically impaired
individuals who displayed unanticipated dissociations of cognitive deficits and abilities. These and a host of other factors alerted psychologists to the necessity for-and to the actuality of-a
vast nonconscious realm of evolved, specialized, computational
problem solvers that construct and interpret the world.
Instead of viewing the world as the force that organizes the
mind, researchers now view the mind as imposing (on an infinitely rich and extensive world) its own pre-existing kinds of
organization-kinds invented by natural selection during the
species' evolutionary history to produce adaptive ends in the
species' natural environment. On this view, our cognitive architecture resembles a confederation of hundreds or thousands of
functionally dedicated computers (often called modules)
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designed to solve adaptive problems endemic to our huntergatherer ancestors. Each of these devices has its own agenda and
imposes its own exotic organization on different fragments of
the world. There are specialized systems for grammar induction,
for face recognition, for dead reckoning, for construing objects,
and for recognizing emotions from the face. There are mechanisms to detect animacy, eye direction, and cheating. There is a
"theory of mind" module, and a multitude of other elegant
machines.
These modules appear to be structured very differently from
the general-purpose cognitive machinery-"attention," "shortterm memory," "category induction," and so on-proposed in
the previous generation of models of the mind. In order to solve
its characteristic domain of problems, a module is designed to
interpret the world in its own pre-existing terms and framework, operating primarily or solely with its own specialized
"lexicon"-a
set of procedures, formats, and representational
primitives closely tailored to the demands of its targeted family
of problem. These are the languages of the human mind: diagnostic facial-muscle configurations defined by an emotionrecognition system that maps the facial expressions of others
onto models of their internal states; a language-acquisition
device whose conceptual primitives include elements such as
"noun phrase" and "verb phrase"; a rigid object mechanics that
construes the world in terms of "solid objects," relative location,
and mutual exclusivity within volume boundaries; socialexchange algorithms that define a social world of agents, benefits, requirements, contingency, and cheating; and-the focus of
this book-a "theory of mind" module that speaks of agents,
beliefs, and desires and links them to a language of the eyes.
This language is generated by still other mechanisms that detect
eye direction and feed the data into a variety of social inference
modules.
The realization that the human mind is densely multimodular has propelled modern psychology into a new theoretical
landscape that is strikingly different from the standard empiricist approaches of the past. In consequence, the outlines of the
psychological science of the coming century are getting clearer.
Foreword
xv
In this new phase of the cognitive revolution, discovering and
mapping the various functionally specialized modules of the
human brain will be primary activities. Even more fundamentally, psychologists are starting to put considerable effort into
making their theories and findings consistent with the rest of the
natural sciences, including developmental biology, biochemistry, physics, genetics, ecology, and evolutionary biology:
Psychology is finally becoming a genuine natural science.
The cognitive revolution solved many of the ontological
problems that had prevented psychological concepts from being
located with respect to the other sciences. (What manner of
thing, after all, was a mental image or an inference or a goal, next
to oxidation or mass or receptor sites?) As a result, the psychological architecture can now be mapped-simultaneously and
complementarily-as a system of computational relationships
and as a physical system that implements these relationships. As
the operation of the genetic code is tracked through molecular
biology and cell biology to developmental neurobiology, the
processes that organize the developing nervous system are
becoming increasingly intelligible. These developmental programs were "designed by selection to build a physical structure
that realizes certain functional informational relationships.
Discovering what these relationships are is the province of still
other fields, such as evolutionary biology and cognitive psychology.
One of the most significant trends in the naturalization of the
psychological sciences is the application of data and conceptual tools forged in evolutionary biology, behavioral ecology, primatology, and human paleoanthropology. These fields have
begun to contribute an increasingly detailed list of the native
information-processing functions that the human brain was
built to execute. Detailed theories of adaptive function can tell
cognitive scientists what modules are likely to exist, what adaptive information-processing problems they must be capable of
solving, and--since form follows function-what kind of design
features they can therefore be expected to have. Evolutionary
biology and related fields can supply this wealth of guidance
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Foreword
because natural selection is the only known natural process that
builds functional organization into the species-typical designs of
organisms. Consequently, all reliably developing functional
mechanisms in a species' psychological architecture must (1)be
ascribed to the operation of natural selection, (2) be consistent
with its principles, and indeed (3)be organized and specifically
designed to solve the narrowly identifiable sets of biological
information-processing problems defined by selection operating
within the context of a species' ancestral mode of life. For
humans, of course, this means the world of ancestral huntergatherers, foraging hominids, and even pre-hominid primates.
Simon Baron-Cohen's trailblazing research gives us a preview of what psychological science will look like in the new century. In this conversational, understated volume, he attacks
some of the most fundamental questions about how human
beings mentally construct their commonly inhabited social
world. He explores how a universal, evolved language of the
eyes, which is mutually intelligible to all members of our species,
can bring two separate minds into an aligned interpretation of
their interaction. What we take for granted-the achievement of
coordinated models of our mutual social interactions-he shows
to be a triumph of automated modules and evolutionary cognitive engineering. Baron-Cohen lays out a series of elegant
hypotheses outlining the design features and interrelationships
of the modules responsible for these daily triumphs: an eyedirection detector, an intentionality detector, a shared-attention
module, and so on. In showing how his proposals account for
many dimensions of human social and mental life, he goes far
beyond his own penetrating cognitive experiments and neuroscience research. In building his account, he weaves together a
seamless tapestry from cognitive science, developmental psychology, primatology, philosophy, cognitive neuroscience, evolutionary biology, anthropology, neurology, behavioral ecology,
and literature to create the first natural-science account of the
mental machinery that implements the language of the eyes. It is
exactly this focus on integrating-within a framework that
simultaneously reconciles cognitive, evolutionary, and neural
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xvii
levels of explanation-research from so many disciplines that
we suspect will be the most salient characteristic of 2lst-century
psychology.
If we have eye-direction detectors and companion modules
that define and speak the language of the eyes, what do they talk
to? Normal humans everywhere not only "paint" their world
with color, they also "paint" beliefs, intentions, feelings, hopes,
desires, and pretenses onto agents in their social world. They do
this despite the fact that no human has ever seen a thought, a
belief, or an intention. A growing community of cognitive scientists has concluded that humans everywhere interpret the
behavior of others in these mentalistic terms because we all
come equipped with a "theory of mind" module (ToMM) that is
compelled to interpret others this way, with mentalistic terms as
its native language. We are "mindreaders" by nature, building
interpretations of the mental events of others and feeling our
constructions as sharply as the physical objects we touch.
Humans evolved this ability because, as members of an intensively social, cooperative, and competitive species, our ancestors' lives depended on how well they could infer what was on
one another's minds. Precisely because such an interpretive system does model the world in terms of unobservable entities
(thoughts, intentions, beliefs, and desires), it needs to be coupled
to confederate modules that can construct a bridge from the
observable to the unobservable. Unobservable entities are invisible to association-learning mechanisms, but they are "visible,"
over the long run, to natural selection. As chance created alternative cognitive designs, this process "selected" those that
implemented the best "betting" system. Over innumerable generations, the evolutionary process selected for modules interpenetrating our perceptual systems that could successful isolate,
out of the welter of observable phenomena, exactly those outward and visible signs in behavior that reliably signaled inward
and invisible mental states. These modules were built to expect,
hook onto, and exploit patterns in the observable world that
they already know how to recognize, and to use these targeted
cues to fill in the blanks in the ToMM's pre-existing models of
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other people's mental states. By linking observable cues (such as
direction of gaze) to representations of unobservable mental
states (such as wants and beliefs), they create what one can think
of as the "psychophysics" of the social world.
Yet even well-designed machinery can break down. When
the machinery is fundamental to the operation of our minds, the
results can be tragic-and deeply illuminating for the cognitive
scientist. Breakdowns of specific modules result in subtractions
from the impaired individual's model of and experience of the
world. A color-blind individual loses one dimension of the visual world. A blind individual loses the entire visual world. But
someone whose ToMM is impaired is blind to the existence of
other minds, while still living in the same physical, spatial, visual, and many-hued world as unimpaired people do. For beings
who evolved to live woven into the minds of mothers, fathers,
friends, and companions, being blind to the existence of others'
minds is a catastrophic loss. Simon Baron-Cohen and his colleagues were the first to propose that an individual with autism
was one whose ToMM had been damaged. They persuasively
explained how this hypothesis accounted for the bizarre constellation of symptoms autistics manifest. By considering what
companion mechanisms the ToMM needed to function, BaronCohen and his colleagues could detect and experimentally track
its computational links to what he has termed the eye-direction
detector (EDD), the shared-attention mechanism (SAM), and the
intentionality detector (ID). As the capstone of this research program, he and his colleagues used these new cognitive models to
develop a method for detecting autism far earlier than anyone
believed possible and successfully tested it on a base population
of 16,000 children.
This sequence of discoveries is one of the key achievements of
modem cognitive science. It deserves the careful attention of
everyone studying social cognition and development, and
because it encapsulates so many of the themes of psychology's
metamorphosis it will become recognized as a milestone in the
naturalization of the psychological sciences.
John Tooby
Leda Cosmides
Preface
This is a complicated book to write, as I have in mind readers
from quite different backgrounds. First, I am writing for my colleagues in the biological and cognitive sciences, whom I hope
will find the theory I advance here of sufficient interest that they
will respond to the ideas and take them further than I have managed to. Second, I am writing for students in psychology (and
related disciplines), for whom I want to make the topic exciting
enough that they decide to stay in the field and make their own
contributions. Finally, and not least, I am writing for the general reader who has no background in psychology but who wants
to keep in touch with where science is going. Keeping in mind
all three types of readers on each and every page requires a fair
degree of acrobatics, I find. At times I have despaired that this
juggling exercise cannot be done. I apologize if I occasionally
lapse in this endeavor.